(1) Field of the Invention
The present invention relates to a technique of cutting a protective tape applied onto the surface of semiconductor wafer on which a pattern is formed.
(2) Description of the Related Art
Conventionally, in a semiconductor wafer manufacturing process, various methods have been employed to process the back surface of semiconductor wafer (hereinafter, referred simply to as xe2x80x9cwaferxe2x80x9d) so that the thickness thereof can be reduced. The methods include mechanical process such as grinding or polishing, or chemical process such as etching. When the above process is used to process the wafer, a protective tape is applied onto the surface of wafer in order to protect the surface of the wafer having wiring pattern thereon.
The protective tape is applied in the following manner. A protective tape is applied onto the surface of the wafer sucked and held on a chuck table, thereafter, the protective tape applied onto the wafer is cut along the outline of the wafer by a cutter unit. In cutting the protective tape, the blade edge of the cutter unit contacting with the protective tape has a specified portion always repeatedly used.
The protective tape is cut, thereafter, unwanted tape is separated and collected, and the work for applying the protective tape is completed.
In recent years, with high-density packaging of semiconductor wafer, there is a tendency for the wafer to be thinned. The wafer is thinned as described above, and thereby, the rigidity of wafer is reduced, and further, warp occurs in the wafer. In order to improve the rigidity of wafer and to prevent the warp, a hard and thick protective tape is applied onto the surface of the wafer.
However, the above hard and thick protective tape is used, and thereby, the following problems arise.
More specifically, the hard and thick protective tape is cut, and thereby, the edge of the cutter contacting with the protective tape early wears; as a result, sharpness of the blade is early lost. In such a state, if the work for cutting the protective tape applied onto the wafer is continued, thrust increases in cutting, and stress by the thrust is applied to the wafer. As a result, there is a problem of breaking down the wafer.
In addition, the blade edge early wears; for this reason, the worn edge must be frequently replaced with a new blade edge. This is a factor of reducing a working efficiency.
The present invention has been proposed in view of the above circumstances. It is, therefore, a principal object of the present invention to provide a method of cutting a protective tape, which can continuously and effectively apply a protective tape onto the surface of semiconductor wafer. Another object of the present invention is to provide a protective tape applying apparatus employing the method same as above.
In order to achieve the above objects, according to one aspect of the present invention, there is provided a method of cutting a protective tape applied on a surface of semiconductor wafer along an outline of the semiconductor wafer by a cutter, comprising:
a step of displacing a contact portion of a blade edge of the cutter to the protective tape so that the protective tape can be cut.
According to the present invention, in the above method of cutting a protective tape, when cutting the protective tape applied onto the semiconductor wafer along the outline of the wafer, the contact portion of the blade edge of the cutter is displaced. Therefore, even if the sharpness of specified blade edge portions is lost, it is possible to cut the protective tape using other sharp blade edge portions. This serves to reduce the stress by thrust applied to the semiconductor wafer when cutting the protective tape. As a result, the semiconductor wafer can be prevented from being broken down.
In addition, the contact portion of the blade edge is displaced, and thereby, it is possible to cut the protective tape by one cutter for a long time. As a result, there is no need of frequently replacing the blade edge with a new blade edge; therefore, a working efficiency can be improved.
In the present invention, preferably, the displacement of the contact portion of a blade edge of the cutter to the protective tape is set to a predetermined interval. Preferably, when cutting the protective tape along an outline of the semiconductor wafer, the contact portion of a blade edge of the cutter to the protective tape is displaced while being vertically moving with the elapse. The interval setup of the contact portion of a blade edge of the cutter to the protective tape is made by vertically moving a cutter unit including the cutter and by vertically moving holding means for placing and holding the semiconductor wafer. The contact portion of the blade edge of the cutter to the protective tape during cutting of the protective tape is displaced with the elapse by vertically moving a cutter unit including the cutter and by vertically moving holding means for placing and holding the semiconductor wafer.
That is, in the process of cutting the protective tape, the contact portion of the blade edge to the protective tape is readily changed. As a result, it is possible to always cut the protective tape using sharp blade edge, and to cut the protective tape by one cutter for a long time.
The protective tape is applied onto the surface of the semiconductor wafer, thereafter, cut. In this case, the protective tape may comprise a single sheet, or may comprise a tape previously laminating the same or different kind of protective tapes. The protective tape may be cut into a shape having a diameter larger than an outer diameter of the semiconductor wafer.
In order to achieve the above objects, according to another aspect of the present invention, there is provided a protective tape applying apparatus for applying a protective tape onto a surface of semiconductor wafer, comprising:
holding means for placing and holding the semiconductor wafer;
tape supplying means for supplying a protective tape to the held semiconductor wafer;
applying means for applying the supplied protective tape onto the surface of the semiconductor wafer;
a cutter unit cutting the protective tape applied onto the semiconductor wafer along an outline of the semiconductor wafer;
first vertical drive means for vertically moving the cutter unit;
first control means for controlling the operation of the first vertical drive means so that a contact portion of a blade edge of the cutter unit to the protective tape can be displaced;
separating means for separating unwanted tape after cutting the protective tape by the cutter unit; and
collecting means for collecting the separated unwanted tape.
According to the present invention, in the protective tape applying apparatus, the protective tape is applied onto the surface of the semiconductor wafer held by the holding means. The protective tape is cut by the cutter unit by along the outline of the semiconductor wafer; in this case, the first control means controls the vertical movement of the cutter unit. Therefore, since the blade edge position of the cutter unit is set and changed by the first control means, the blade edge portion losing sharpness due to wear can be replaced with a sharp blade edge having no wear.
According to the present invention, the apparatus further includes second vertical drive means for vertically moving the holding means, and second control means for controlling the operation of the second vertical drive means so that a contact portion of a blade edge of the cutter unit to the protective tape can be displaced.
With the above construction, the second control means controls the vertical movement of the holding means so that the contact portion of the blade edge of the cutter to the protective tape can be set and changed. Therefore, the blade edge portion losing sharpness due to wear can be replaced with a sharp blade edge having no wear.